The present invention relates to an object detecting actuator and an object detecting switch.
Conventionally, there are known limit switches used on factory production lines to detect that an object such as a product to be processed has been transferred to a predetermined position, and to automatically activate processing machinery. The limit switch is provided with an actuator, and passage of a conveyed object is detected by contact of the object with the actuator.
For example, Japanese Unexamined Patent Publication No. 2006-164665 (published on Jun. 22, 2006) discloses a limit switch that detects the passage of an object by contact with a stainless steel material actuator. The actuator has a roller lever and a roller, and the roller is rotatably attached to the roller lever by means of a rotary shaft. Consequently, friction between the object and the actuator during passage of the object is reduced.
Generally, the roller is constituted by a sintered body of stainless steel material as a porous material, and oil is permeated into a plurality of holes. The oil therefore seeps out onto the surface of the roller when the roller is rotating, and lubrication performance of the contact portions of the rotary shaft and the roller is improved.
In recent years, the loads placed on actuators have been increasing, such as increases in the weight of objects to be detected, and increases in contact frequency or the number of times of contact. Consequently, actuators having an even greater strength are being pursued. For example, high-density sintered bodies (for example, 6.9 g/cm3) are being used to manufacture high-strength actuators.
However, as the loads have been progressively increasing, it has become no longer possible to ensure a sufficient lifespan with actuators manufactured by means of conventional technique.